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Biomedical subjects

M Tsuda

Publications and source records attributed to M Tsuda.

At least 613 records · Page 34Linked to original sources
PubMed1980

Resonance Raman spectra of octopus acid and alkaline metarhodopsins.

The resonance Raman spectra of acid and alkaline metarhodopsins of octopus were measured. The acid metarhodopsin exhibited the Schiff base C = N stretching band at 1655 cm-1 in H2O and at 1625 cm-1 in 2H2O, and therefore the Schiff base is shown to be protonated. The C = C stretching band was observed at 1548 and 1572 cm-1 for acid and alkaline metarhodopsins, respectively. Other Raman lines of octopus acid metarhodopsin were assigned from the data of Cookingham et al. (Cookingham, R.E., Lewis, A. and Lemley, A.T. (1978) Biochemistry 17, 4699-4711). Frequencies of some structure-sensitive Raman lines differed among octopus, squid and bovine metarhodopsins; such differences may be important in interpreting the presence of optical activity in octopus metarhodopsins but its absence in squid metarhodopsins.

Animals↗
PubMed1980

High frequency mobilization of the chromosome of Escherichia coli by a mutant of plasmid RP4 temperature-sensitive for maintenance.

Two mutants of plasmid RP4 temperature-sensitive for maintenance were isolated and one of them (pTH 10) was extensively studied. Cells carrying pTH10 showed temperature-sensitive drug resistance from which we isolated a number of temperature-independent derivatives. Almost all of them were Hfrs donating chromosomal genes to recipient bidirectionally from different points of origin. The Hfrs may be formed in two steps: (1) the transposon (Tn 1) carried by pTH 10 translocates into the host chromosome, and (2) pTH 10 is integrated in the host chromosome by reciprocal recombination between the TN 1 s, one situated on pTH 10 and another on the host chromosome. That temperature-independent drug resistance selects for this type of derivative, was supported by the following observations: (1) Hfrs thus obtained were usually unstable and segregated at high frequency 'revertants' showing temperature-sensitive drug resistance when they were cultivated at 30 degrees C. (2) The 'revertants' cured of pTH 10 were still ampicillin resistant, indicating existence of Tn 1 inserted in the host chromosome. (3) Tn 1 insertions found in these derivatives mapped in the vicinity of points of origin of the original Hfrs. (4) When new Hfrs were constructed by: (a) transduction with Plkc on Tn 1 insertions found in derivatives of Hfrs, (b) introduction of pTH 10 into the transductants,and (c) isolation of clones of temperature-independent drug resistance from such pTH 10 carrying stains, they had similar characteristics to the original Hfrs from which Tn 1 insertions were derived. Possibilities for genetic manupulation using pTH 10 in a wide range of Gram-negative bacteria are discussed.

Chromosomes, Bacterial↗
PubMed1980

Inactivation of mutagens from pyrolysates of tryptophan and glutamic acid by nitrite in acidic solution.

The mutagenic aromatic amines Trp-P-1, Trp-P-2 and Glu-P-1, isolated frm pyrolysates of tryptophan and glutamic acid, at the concentration of 0.025 mM were treated with 0.05 mM nitrite at various pH values at 37 degrees C. The resulting reaction mixtures were tested for mutagenicity towards Salmonella typhimurium TA98 and TA100. When treated with nitrite at this physiologically realistic concentration, these mutagenic aromatic amines were readily converted to extremely weak or non-mutagenic deaminated compounds. These deaminated products were identified as the corresponding hydroxy compounds by mass and proton magnetic resonance spectroscopies. Comparative kinetic studies were made on the disappearance of the mutagenic aromatic amines. The half-life (t1/2 of Glu-P-1 on treatment with nitrite at pH 1.6 was less than 5 min, and those of Trp-P-1 and Trp-P-2 were 95 and 105 min, resp.

Amines↗
PubMed1980

Effect of high pressure on the absorption spectrum and isomeric composition of bacteriorhodopsin.

The effects of high pressure upon the absorption spectra and isomeric composition of the dark (bRD) and light adapted (bRL) forms of bacteriorhodopsin were examined. Pressure favors the 13-cis form of bacteriorhodopsin (bR13-cis). The equilibrium isomeric composition and absorption spectra of bacteriorhodopsin samples at a given pressure were the same starting from either light or dark adapted bacteriorhodopsin. From the effect of pressure on the equilibrium constant between bRall-trans in equilibrium bR13-cis in the dark, the molar volume change between bRall-trans and bR13-cis was found to be -7.8 +/- 3.2 ml/mol. This volume change suggests a difference in conformation between dark- and light-adapted bacteriorhodopsin, but the magnitude of the change is small, involving only a small number of the protein residues.

Bacteriorhodopsins↗
PubMed1980

Selective inhibition by neuraminidase of insulin action on hexose metabolism of mouse adipocytes.

Mouse adipocytes treated with neuraminidase showed a decreased response of glucose oxidation to insulin although insulin binding to the cells was normal. The decreased response was associated with the release of sialic acids from the cells by enzyme digestion. The hormone action on 2-deoxyglucose uptake was also decreased. However, the hormone action on glyceride-glycerol synthesis or lipogenesis from glucose was unaltered when enzyme-treated cells were incubated with higher glucose concentration (greater than or equal to 5 mM). However, at lower glucose concentrations (< 5 mM), in which glucose transport was a rate-limiting step, the hormone action was markedly decreased. When fructose was used as a substrate, the enzyme-treated cells showed an impaired response to insulin in fructose oxidation but not in glyceride-glycerol synthesis and lipogenesis from fructose. These results suggest that the postreceptor systems of insulin action on glyceride-glycerol synthesis and lipogenesis from hexose are different from those of the hormone action on hexose transport and oxidation. Furthermore, alteration in insulin-sensitive metabolic profiles may be caused, in part, by changes in glycoproteins and/or glycoplipids on the cell surface.

Adipose Tissue↗
PubMed1980

LiF and CaF2: Dy thermoluminescent dosimeters.

A study has been made of the characteristics of the LiF glow curve as a function of annealing temperature and time. Two annealing methods with different annealing time were studied. The annealing by a hot air stream may anneal quickly. The annealing method affects the shape of the glow curve. If the annealing procedure and the measurement time after irradiation are constant, the fading does not affect the results, except over a long time for uses in personnel dosimetry. For LiF, TLD-600 had a higher sensitivity for 60Co gamma rays than TLD-100 and -700 by a factor of 1.23. For CaF2: Dy, glow curves of unusual shape were obtained, and its relative response was several times greater than that of normal phosphors.

Calcium Fluoride↗
PubMed1979

Characteristics of phospholipids in microvillar membranes of octopus photoreceptor cells.

Characteristics of lipids in the microvillar membranes of octopus photoreceptor cells were studied in order to obtain some information on the membrane environment with rhodopsin in the invertebrate. (1) The membranes contain lipid and protein in almost equal proportion. The majority of lipids are phospholipids. Neutral lipids make up 16% of the total lipids, the major constituent of which is cholesterol. (2) Phosphatidylethanolamine and phosphatidylcholine are the major phospholipids. Phosphatidylserine, ceramide 2-aminoethylphosphonate and sphingomyelin occur as minor components. An unidentified alkaline and acid stable phospholipid was found. (3) The predominant fatty acids of phosphatidylethanolamine and phosphatidylcholine are highly unsaturated such as 22 : 6, 20 : 5 and 20 : 4. The 22 : 6 and 20 : 5 are exclusively linked at the 2-position, but the 20 : 4 is linked significantly at the 1-position of the phospholipids. (4) Major molecular species are 16 : 0/22 : 6 (48.4%) and 16 : 0/20 : 4 (19.6%) in phosphatidylcholine, and 20 : 4/22 : 6 (50.7%) and 16 : 0/22 : 6 (25.6%) in phosphatidylethanolamine.

Animals↗
PubMed1979

Optical activity of octopus metarhodopsins.

The optical activity of octopus rhodopsin, acid metarhodopsin and alkaline metarhodopsin was studied by a sensitive and rapid CD apparatus. For sometime it has been thought that cephalopod metarhodopsins do not have any optical activity associated with their main absorption band. However, the present work shows that acid metarhodopsin in digitonin has a positive CD band at 498 nm and a negative CD band at 436 nm and alkaline metarhodopsin has a negative CD band at 381 nm. Detergent affected the wavelength of the CD peak of the visual pigments though the pattern of the spectrum was similar. From these results it is concluded that the conformation of all-trans retinal in octopus metarhodopsin is influenced by the asymmetric conformation of the protein near the retinal and therefore inducing optical activity.

Animals↗